Single mother in need of explanation

I am unable to look at the video as i am on dial-up. Before continuing, may i say that firecrackers are dangerous and a finger, or hand, or eye can be destroyed without the proper care in handling and use of shielding?

Here is the idea: in the car are pistons (moveable cylindrical devices) that are sealed in a cylindrical chamber so that they can only move up and down. Simplisticly speaking, when they are at the top, a mixture of gasoline and air is introduced and exploded with a spark. The resulting pressure pushes the piston down - and that motion is indirectly transferred to move the car. A firecracker can be exploded also, and if a fixture is properly engineered to take advantage of that, the expanding gasses could be used to impart motion to a wheel (the transfer would be more direct than in a car).

The engineering of that fixture must be carefully done using materials that will not be cracked or shattered by the explosion (think